The invention relates to a method and apparatus for separation of fluids by permeation in at least one permeation stage or cell provided with a wall which is differently permeable by such fluids or by their components, and which stage is subdivided by the wall into an inlet portion and a permeate portion, wherein the fluid is charged to that side of the membrane which is associated with the infeed portion and the less strongly permeating component is withdrawn at such side, while the more strongly permeating component is withdrawn at the permeate side.
The fluids involved herewith can be in the form of liquids, gases, solutions or dispersions. As a permeable wall, a membrane is used from a suitable material, e.g. of the type of a plastic film. To the known applications of such method belongs e.g. the separation of helium from natural gas. A method of this type can also be used in the field of enrichment with oxygen, with uranium or the like. In another application, it is possible, under the use of the principle of reverse osmosis, to separate salt components from seawater for the purpose of producing fresh water. For this purpose, a relatively high energy consumption is required as pressure values of between 50 and 100 bar must be generated.
All installations thus far used for such separation are relatively expensive with regard to their structure. A number of permeation stages in the form of membrane modules are interconnected in a cascade fashion. Such cascade interconnections, however, have the drawback that the required exchange surfaces must be relatively large and that, also, the drive of such installations is very demanding on energy. The reason for this is, among other things, the necessity of circulating relatively large volumes of fluid, namely with a great number of feeding organs or fluid movers.
Proceeding from the above, it is an object of the invention to provide a method suitable for separation of fluids by permeation which can be carried out in technically less expensive devices and at smaller operation costs.